A "sensitivity" test to determine the chemotherapeutic responsiveness of human tumors has been developed at the Mason Research Institute in Worcester. Human tumors are surgically implanted in the subcapsular region of the kidney in normal mice. Various drugs are administered to the mice, and the change in the size of the tumor is measured after six days. Chemotherapeutic agents which cause tumor regression in this mouse model are expected to have a high chance of success in the human. The role of the subrenal capsule assay in determining treatment regimens for patients with cancer will be assessed at the University of Massachusetts Medical Center in conjunction with other area hospitals.